Smoke suppressant fuel mixtures

ABSTRACT

A LIQUID FUEL COMPOSITION HAVING REDUCED SOOT AND SMOKING CHARACTERISTICS IS FORMED BY ADMIXING A MAJOR PROPORTION OF A LIQUID HYDROCARBON FUEL AND A MINOR PROPORTION, RESPECTIVELY, OF AN ETHER AND A GROUP II-A METAL SULFONATE WHEREIN THE CONCENTRATION OF GROUP II-A METAL IS FROM ABOUT 0.007 TO 0.1% BE WIGHT. A PREFERRED FUEL COMPOSITION COMPRISES A DIESEL FUEL ADMIXED WTIH A BARIUM ALKARYL SULFONATE AND AN ALKYL ETHER OF AN ALKYLENE GLYCOL, SAID GLYCOL ETHER HAVING FROM 3 TO 10 CARBON ATOMS, WHEREIN THE CONCENTRATION OF BARIUM METAL IS FROM ABOUT 0.04 TO 0.08% BY WEIGHT.

UnitedStates Patent ,594,140 SMOKE SUPPRESSANT FUEL MIXTURES Elmer J. Badin, Hightstown, N.J., assignor to Cities Service Oil Company, Tulsa, Okla. No Drawing. Filed Nov. 26, 1968, Ser. No. 779,219 Int. Cl. Cl1/18, 1/24 US. Cl. 44-76 11 Claims ABSTRACT OF THE DISCLOSURE A liquid fuel composition having reduced soot and smoking characteristics is formed by admixing a major proportion of a liquid hydrocarbon fuel and a minor proportion, respectively, of an ether and a Group II-A metal sulfonate wherein the concentration of Group II-A metal is from about 0.007 to 0.1% by weight. A preferred fuel composition comprises a diesel fuel admixed with a barium alkaryl sulfonate and an alkyl ether of an alkylene glycol, said glycol ether having from 3 to 10 carbon atoms, wherein the concentration of barium metal is from about 0.04 to 0.08% by weight.

BACKGROUND OF THE INVENTION This invention relates to new liquid fuel compositions. In particular, it relates to new diesel fuel mixtures with reduced smoke and soot forming properties.

The petroleum industry has encountered serious problems in supplying the demand for middle distillate and heavy residual oils suitable for injecting into compression ignition engines which will not contribute materially to the pollution of the atmosphere through smoke and soot production. Coupled with this specific need for a diesel fuel mixture with reduced smoking characteristics, there is also an urgent need for liquid hydrocarbon fuel mixtures having improved combustion characteristics for spark ignition and jet engines.

Attempts have been made to reduce the soot formed during the oxidation of liquid hydrocarbon fuels. By Way of example, certain metallic smoke suppressant mixtures have been employed in compression ignition engines, but objections to these mixtures are that they leave deposits in engine crankcases as a result of blowby from cylinders, can be expensive to produce and package, and can form undesirable combustion products in proportion to their content of metal.

Accordingly, there exists an urgent need to produce a hydrocarbon fuel mixture having reduced smoke and soot forming properties free of the side effects and deficiencies of the prior art.

SUMMARY OF THE INVENTION It is an object of this invention to provide a liquid hydrocarbon fuel mixture and in particular a diesel fuel mixture, which has reduced smoke and soot forming properties.

It is another object of this invention to provide a fuel mixture having reduced soot and smoke forming characteristics which produces a minimum of ash upon combustion.

It is another object of this invention to provide an improved method for operating an internal combustion engine, and particularly a compression ignition engine.

Other aspects, objects and advantages of this invention will be evident to those skilled in the art in view of this disclosure.

The objects of this invention are met by dispersing or dissolving in liquid hydrocarbon fuels having a tendency decyl, eicosyl, pentacosyl, phenyl ice to form soot and smoke on combustion, a minor amount of an ether and a Group II-A metal sulfonate wherein the concentration of the Group IL-A metal is from about 0.007 to 0.1% by weight based on the total weight of the fuel mixture. Generally, the concentration of ether in the sulfonate-fuel mixture is from about 0.05 to 5% by weight.

Mixtures of diesel fuel, an ether and a barium hydrocarbyl sulfonate have particularly significant reduced smoke and soot forming properties.

Liquid hydrocarbon fuel mixtures having further reduced soot and smoke characteristics are obtained when glycol ethers, particularly mono or dialkyl ethers of ethylene glycol are employed. A particularly preferred fuel mixture is diesel fuel in admixture with from about 0.2 to 0.5% by weight of l-methoxy-Z-propanol and from about 0.04 to 0.08% by weight of barium metal present as a barium alkaryl sulfonate having a molecular weight of from about 900 to 1100. Enhanced results are also obtained when the other is the dimethyl ether of ethylene glycol.

Further, according to the invention there is provided a method for operating an internal combustion engine which comprises passing a liquid hydrocarbon fuel mixture of the invention through the fuel supply system to the combustion chamber of said engine and causing ignition of the fuel therein in normal fashion. This method of operation can be employed in operating a compression ignition engine utilizing the diesel fuel mixtures of this invention.

The sulfonic acids from which the sulfonates employed in the present invention are formed are those having the following structural formula:

R-SOgH where R is a hydrocarbyl radical. v

R may be an alkyl, alkenyl, aryl, alkaryl, aralkyl or alicyclic radical. Examples of suitable R groups are: methyl, propyl, 2-ethylhexyl, neodecyl, dodecyl, octanaphthyl, benzyl, cresyl, ethylphenyl, phenylhexyl, cyclohexyl, cyclopropyl, butenyl, linoleyl, and the like.

Examples of sulfonic acids employed as sulfonates are: methanesulfonic acid, decanesulfonic acid, Z-ethylhexanesulfonic acid, pentanesulfonic acid, phenylmethanesulfonic acid, decylbenzenesulfonic acid, naphthalenesulfonic acid, octenesulfonic acid, cyclohexanesulfonic acid, and the like, and mixtures thereof. Further mixed (unsymmetric) sulfonates may be employed to raise or lower the metal content of the fuel mixtures as desired. Mixtures of symmetric and unsymmetric sulfonates are also employed.

Some specific sulfonates useful in this invention include:

and mixtures thereof.

The ethers employed in the present invention are, in general, those having the following structural formulas:

R(OR'-)n OR" wherein n is an integer preferably between about 0 to 10 and especially between about 1 to 3; R is a hydrocarbyl radical, R" is hydrogen or hydrocarbyl radical, such that when n is a whole integer, R" is hydrogen or hydrocarbyl, and when n is zero, R" is hydrocarbyl, and R is a hydrocarbylene radical, such as methylene, ethylene or the like; and

wherein n is an integer preferably having the value of 1 or 2, and R and R' are hydrocarbylene radicals; Wherein the total number of carbon atoms in either molecule is preferably less than about 30.

Thus, when R and R" are hydrocarbyl radicals, typical groups include, for instance: alkyl, alkenyl, aryl, alkaryl, aralkyl, or alicyclic radicals. Examples of suitable hydrocarbyl radicals are: methyl, ethyl, propyl, butyl, isohexyl, 2-ethylhexyl, neodecyl, dodecyl, octadecyl, eicosyl, nonacosyl, phenyl, naphthyl, benzyl, tolyl, ethylphenyl, phenylhexyl, cyclohexyl, cyclopropyl, cyclopentyl, butenyl, octenyl, linoleyl, etc.

When R and R' are hydrocarbylene radicals, typical groups include, for example: alkylene, arylene, alkarylene, aralkylene, alkenylene or alicyclene radicals. Suitable hydrocarbylene radicals are: methylene, ethylene, propylene, isohexylene, decylene, phenylene, cyclohexylene, pentenylene, etc.

Examples of simple ethers useful in this invention are: diethyl ether, diisopropyl ether, methyl tert-butyl ether, ethyl n-butyl ether, decyl butyl ether, nonacosyl methyl ether, allyl ethyl ether, vinyl isobutyl ether, cyclopropyl methyl ether, cyclobutyl ether, methyl ethyl ether, benzyl methyl ether, benzyl ethyl ether, phenyl ether, anisOle, bis(2-chloroisopropyl) ether, and the like.

Examples of heterocyclic ethers useful in this invention are: such heterocyclic monoethers as tetrahydrofuran, ethylene oxide, propylene oxide, furan; such heterocyclic diethers as para-dioxane; meta-dioxane; dioxolanes; 2-(3-heptyl) 1,3-dioxolane; 2-(3-heptyl) 1,3-dioxan-5-ol; 2-(3-heptyl) l,3-dioxolane-4-methanol; and such heterocyclic triethers as symtrioxane; ethyltrioxane; and the like.

Typical fuel mixtures of the invention include any ether, and any sulfonate, selected from the following examples, in admixture with a liquid hydrocarbon fuel.

Ether: Group II-A sulfonate Monophenyl ether of ethylene glycol.

DESCRIPTION OF PREFERRED EMBODIMENTS Enhanced smoke suppressant characteristics are obtained when barium sulfonates are employed.

Generally it is preferred that fuel-soluble sulfonic acids be used, such as high molecular weight petroleum sulfonic acids, including mahogany acids.

Naturally occurring alkaryl hydrocarbons, such as those found in mixed kerosene fraction of petroleum, are suitable as the hydrocarbyl substituents of the sulfonic acids. These sulfonic acids may be prepared according to the processes disclosed in US. 2,395,713 and US. 2,388,677 and refined according to US. 2,387,866.

synthetically produced mixed alkaryl sulfonates of Group II-A metals, especially barium, having two alkyl groups per aromatic group are especially suited. It is particularly preferred that each alkyl group of the mixed sulfonates is a linear group of from about 14 to 18 carbon atoms, said sulfonate having a molecular weight of from 800 to 1,500, preferably from 900 to 1,100.

Examples of preferred sulfonates include:

barium 2-hexadecyl-3-heptadecylbenzenesulfonate;

barium 2- 3-methylpentadecyl) -6-octadecylbenzenesulfonate;

barium 2 octadecyl 8 (2 ethylhexadecyl) naphthalenesulfonate;

barium 2 ethyltetradecyl 8 (S-methyltetradecyl) naphthalenesulfonate;

and mixtures thereof and especially those having a molecular weight of about 1,000.

Further, it will be recognized that derivatives of the aforementioned sulfonates having groups, preferably polar, substituted in place of hydrogen may also be incorporated into hydrocarbon fuels. substituents must be essentially non-reactive to the fuel and include, for example, such polar groups as halogen, amino, nitro, nitrate, hydroxyl, and the like.

Generally the preferred ethers are those normally liquid mono or diethers of polyols, soluble in fuel. Examples of these ethers are: monomethyl ether of diethylene glycol, monoethyl ether of diethylene glycol, dimethyl ether of propylene glycol, monomethyl ether of triethylene glycol, diethyl ether of dipropylene glycol, and the like. Alkyl ethers of polyoxyalkylene glycols having from about 3 to 10 carbon atoms are particularly preferred.

Especially suitable ethers are the monoalkyl ethers of glycols and in particular, of ethylene glycol such as: monoethyl ether of ethylene glycol, monopentyl ether of ethylene glycol, mono(2-ethylbutyl) ether of ethylene glycol, monopentyl ether of ethylene glycol and monopropyl ether of propylene glycol; and the dialkyl ethers of glycols and, particularly, of ethylene glycol, such as dipropyl ether of ethylene glycol, diethyl ether of ethylene glycol, and di-butyl ether of ethylene glycol.

Fuel mixtures of sulfonates and dialkyl ethers of ethylene glycol, and particularly of dimethyl ether of ethylene glycol, commonly called glyme, generally exhibit improved cetane numbers, as compared to diesel fuels without said ethers, as well as effective soot and smoke reductions. This improvement is also seen in such dialkyl ethers of polyoxyethylene glycols, as dimethyl ether of diethylene glycol, diethyl ether of diethylene glycol, and dimethyl ether of triethylene glycol and the like. Accordingly, such ethers comprise another particularly preferred class of ethers.

An ether producing unusually good soot and smoke reduction. in fuels in conjunction with the sulfonates of this invention is 1-methoxy-2-propanol.

It will be recognized that the derivatives of the aforementioned ethers having groups, preferably polar, substituted in place of hydrogen may also be incorporated into fuels. Such substituents must be essentially non-reactive to fuel and include such polar groups as halogen, amino, nitro, nitrate, hydroxyl, and the like.

Preferred mixtures of the invention include:

Monomethyl ether of propylene glycol Barium 2- (2-ethylheptyl benzenesulfonate Diesel fuel Diethyl ether of pentylene glycol Barium 1,2,3-tridodecylnaphthalenesulfonate Diesel fuel Monomethyl ether of triethylene glycol Barium 3-octadecylanthracenesulfonate Diesel fuel Especially suitable diesel fuel mixtures of this invention are:

1-methoxy-2-propanol Barium-3-decyl-4-nony1benzenesulfonate Diesel fuel Monomethyl ether of ethylene glycol Barium 2-dodecyl-3-dodecylbenzenesulfonate Diesel fuel Dimethyl ether of ethylene glycol Barium 2-heptadecyl-8-decylnaphthalenesulfonate Diesel fuel Dimethylether of diethylene glycol Barium 2-tridecyl-4-pentadecylbenzenesulfonate Diesel fuel In order to reduce the amount of visible black soot and smoke emitted from internal combustion engines significantly, the Group II-A metal sulfonates are employed in minor amounts, at least at about 0.007% by weight Group II-A metal, as a Group II-A metal sulfonate. When amounts of below about 0.007% by weight of Group II-A metal are employed, no practical smoke reductions are achieved.

Generally, no more than about 0.1% by weight Group II-A metal, present as a Group II-A metal sulfonate, is employed. If greater amounts are employed, no further substantial visible smoke and soot reductions are obtained. Also, if Group II-A metal, as sulfonate, is employed in excess of about 0.1% by weight, detrimental affects are observed in engine performance, characterized,

in part, by such conditions as stalling and bucking.

For best results it is preferred that the Group II-A metal sulfonates, especially barium alkaryl sulfonates, be employed to supply from about 0.04 to 0.08% by weight Group II-A metal.

The ethers are utilized in amounts necessary to produce a significant reduction in the smoke and soot forming characteristics of the fuel mixture. For this purpose, generally at least about 0.05% by weight of ether is employed. Although amounts in excess of about 5% by weight may be employed, practical smoke reductions are achieved with lesser amounts.

Preferably the ethers, and particularly allyl ethers of alkylene glycols having from about 3 to 11 carbon atoms, are employed in amounts from about 0.1 to 1% by weight.

Best results are attained when from about 0.2 to 0.5% by Weight of ether is employed.

The previous weight percents are based upon the weight of Group II-A metal or ether as compared to the total Weight of the fuel mixtures.

If need be, to enhance the solution of Group II-A metal sulfonates in hydrocarbon fuels, particularly diesel fuels, it may be advisable to admix the sulfonates with an inert petroleum solvent, such as petroleum ether, Varsol, white oil, the aforementioned ethers, alcohols, especially glycols, and the like and mixtures thereof, in amounts sufficient to form a liquid concentrate with greater solubility in these fuels. On the other hand, the sulfonates can be dispersed in the fuel in finely divided form.

Preferably, to prepare the fuel, sulfonate and ether mixtures, the sulfonate is dissolved or dispersed in the fuel and thereafter the ether is added to the sulfonate-fuel mixture. If desired, the sulfonate may be initially dissolved or dispersed in the ether and the resulting sulfonate-ether concentrate combined with the liquid hydrocarbon fuel.

In general, any liquid hydrocarbon fuel including heating fuels, and particularly those fuels useful in internal combustion engines can be employed as the fuel component of the compositions of this invention. It is preferred that the liquid hydrocarbon fuel be a diesel fuel having an initial boiling point of about 300 F. and an end distillation point of about 750 F. Diesel fuels having a boiling range of from about 400 F. to about 675 R, such as No. 2 diesel fuel, are especially preferred.

The following examples are given to further illustrate the nature of the invention and are not limitative of scope.

EXAMPLE I In order to evaluate the new smoke suppressant mixtures, 0.3% by weight of the dimethyl ether of ethylene glycol and 0.3% by weight of a barium alkaryl sulfonate (14.5 weight percent Ba; molecular weight about 1000) were sequentially dissolved in a diesel fuel at room temperature with mechanical stirring.

The following examples are given to further illustrate possessing the following characteristics:

(1) Gravity, API 32.9 (2) Flash point, F. 108 (3) Distillation:

10% recovered, F 419 recovered, F. 587 Residue, percent .15 (4) FIA:

Aromatics, percent 31.0 Olefins, percent i 0 Saturates, percent 69.0

The novel smoke suppressant mixtures were evaluated in a 4-cylinder John Deere Model 3020 tractor engine equipped with a Hartridge smoke meter. An exhaust probe was inserted in the exhaust pipe about 4 feet from the exhaust manifold. The probe was connected to a 2-way valve of the smoke meter.

Firstly, the engine was warmed up on the base fuel at a condition wherein no visible smoke was observed in the exhaust gases. The fuel flow was increased until it was about 22 pounds per hour, generally corresponding to the appearance of visible black smoke in the exhaust gases.

The smoke suppressant fuel mixture of the invention was then substituted for the base fuel and the engine was run about 5 minutes to allow stabilization. The smoke meter reading was then recorded. The cycle of base fuel and additive fuel was repeated two additional times.

On the Hartridge scale, the value of represents completely black smoke while 30 and below represents a clear exhaust acceptable under all running conditions. Accordingly, the raw smoke values obtained from the smoke meter were subtracted from the no smoke base of 30 to more clearly define the degree of smoke reduction obtained. Use of this procedure gave an adjusted Hartridge smoke number labeled herein by HSN, and percent smoke reduction is then represented by:

[ base udditive] base] The following table illustrates the effectiveness of the novel fuel mixture. In the table the adjusted Hartridge smoke numbers (HSN) are given as the average of three consecutive runs.

It should be noted that the components of the fuel mixture, when tested individually, showed less effectiveness in reducing visible soot and smoke than the combination thereof. This demonstrates that synergistic promotion of smoke and soot suppression is obtained when Group II-A metal sulfonates and ethers are admixed in fuels.

The results of the preceding example demonstrate the enhanced effectiveness of fuel mixtures of barium hydrocarbyl sulfonates and of alkyl ethers of ethylene glycol, and especially fuel mixtures of dimethyl ether of ethylene glycol and barium alkaryl sulfonates in reducing smoke and soot. Similar results are also obtained when other combinations of ethers and Group II-A metal sulfonates are substituted for the sulfonate and ether of the above example. Satisfactory results are obtained when other ethers such as methyl ethyl ether, diethyl ether of diethylene glycol, dioxane, and dibenzyl ether are substituted for the dimethyl ether of ethylene glycol. Further, when other sulfonates, for instance, barium decanesulfonate, strontium 2-propylheptanesulfonate, calcium npentylbenzenesulfonate, magnesium cyclobutanesulfonate, beryllium linoleylsulfonate naphthalenesulfonate are substituted for the above tested sulfonate, satisfactory results are obtained.

EXAMPLE II In order to further demonstrate visible smoke and soot reduction in mixtures of hydrocarbon fuels, selected quantities of the synthetic barium alkaryl sulfonate previously employed and l-methoxy-Z-propanol were admixed in the No. 2 diesel fuel of Example I and then tested in the John Deere 4 cylinder engine according to the procedure of Example I. The smoke reductions are reported in accordance with the equation of the previous example. The following table shows the results of the tests:

RESULTS OF SMOKE AND SOOT SUPPRESSION TESTS Wt. Wt. HSN Percent percent percent of HSN visible Additive in additive met base of fuel smoke base fuel in fuel in fuel fuel mixture reduction Barium alkaryl sulfonate 0. 05 0. 007 43 39 9 1-methoxy-2- propanol 0. l 5

Total 0. 10

Barium alkaryl sulfonate 0. l 0. 014 44 37 16 l-methoxy-Z- propanol 0. 1

Total 0.2

B arium alkaryl sulfonate 0. 4 0. 058 43 21 51 1-methoxy-2- propanol 0. 4

Total 0. 8

Barium alkaryl s onate 0. 05 0. 007 45 42 7 l-methoxy-Z- propanol 0. 2 40 40 0 When the barium alkaryl sulfonate was tested alone, according to the above procedure, at concentrations of 0.014% and 0.058% barium metal, respectively, the smoke reductions observed were significantly less than the above tested sulfonate-ether fuel mixtures having the same metal concentrations.

The ether employed, l-methoxy-Z-propanol, was assigned a zero rating for individual smoke reduction because the smokemeter apparently did not detect the relatively small decrease produced imvisible smoke and soot.

The results illustrate that fuel mixtures of Group II-A metal sulfonates and ethers suppress visible smoke and soot produced upon combustion.

If desired, the fuel compositions of this invention may additionally contain oxidation inhibitors, corrosion in- 8 hibitors, antifoam agents, other smoke suppressants, sludge inhibitors, color stabilizers and other additional agents adapted to improve the fuels in one or more respects. Further, detergents, such as metal salts of monoesters of sulfuric acid formed from aliphatic alcohols containing from 8 to 18 carbons, metal salts of di-(2-ethylhexyl)sulfosuccinic acid, and especially Group II-A salts, particularly barium salts, and mixtures thereof may be additionally incorporated to the additives.

It will be understood that the specific embodiments set forth hereinabove are illustrative only and that the invention is not to be limited except as set forth in the following claims.

Therefore, I claim:

1. A fuel composition having reduced smoke and soot forming properties comprising a major proportion of a liquid hydrocarbon fuel and a minor proportion, respectively, of an alkyl ether of an alkylene glycol in which the glycol ether has up to 8 carbon atoms and a Group II-A metal sulfonate wherein the concentration of the Group II-A metal is from about 0.007 to 0.1% by weight based on the total weight of the fuel mixture. I

2. The composition of claim 1 in which the Group II-A metal sulfonate is a barium hydrocarbyl sulfonate.

3. The composition of claim 2 in which the barium hydrocarbyl sulfonate is a barium alkaryl sulfonate.

4. The composition of claim 1 in which the ether is present in amounts from 0.05 to 5% by weight.

5. The composition of claim 4 in which the ether is present in amounts from about 0.1 to 1% by Weight, based on the total weight of the fuel mixture.

6. A fuel composition having reduced soot and smoke forming properties comprising a diesel fuel, a barium alkaryl sulfonate, and an alkyl ether of an alkylene glycol, the glycol ether having up to 8 carbon atoms, the concentration of the barium metal is from about 0.04 to 0.08% by weight, the concentration of the other is from 0.2 to 0.5% by weight and wherein the concentration of said barium and said ether are based on the total weight of the fuel mixture.

7. The composition of claim 6 in which the sulfonate is a barium alkaryl sulfonate having a molecular weight of from about 900 to 1100 and the ether is l-methoxy-Z- propanol.

8. The composition of claim 7 in which the dimethyl ether of ethylene glycol is substituted for 1-methoxy-2- propanol.

9. In the method of operating an internal combustion engine wherein a liquid hydrocarbon fuel is passed through a fuel supply system into a combustion chamber of said engine and said fuel is caused to ignite therein, the improvement comprising operating said engine on a hydrocarbon -fuel containing a minor proportion of an alkyl ether of an alkylene glycol in which the glycol ether has up to 8 carbon atoms and a Group II-A metal sulfonate wherein the concentration of the Group II-A metal is from about 0.007 to 0.1% by weight based on the total weight of the fuel mixture.

10. In the method of operating a compression ignition engine wherein a diesel fuel is passed through a fuel supply system into a combustion chamber of said engine and said fuel is caused to ignite therein, the improvement comprising operating said engine on a diesel fuel containing a barium alkaryl sulfonate and an alkyl ether of an alkylene glycol, the glycol ether having up to 8 carbon atoms, the concentration of the barium metal is from about 0.04 to 0.08% by weight, the concentration of the ether is from about 0.2 to 0.5 by weight and the concentration of said barium metal and said ether are based on the total weight of the fuel mixture.

11. The method of claim 10 in which the fuel mixture is a diesel fuel containing a barium alkaryl sulfonate having a molecular weight of from about 900 to 1100 and the ether is the dimethyl ether of ethylene glycol.

(References on following page) n MW MW 9 Refexences Cited UNITED STATES PATENTS FOREIGN PATENTS 1,003,746 9/1965 Gtat Britain 4477 DANIEL E. WYMAN, Primary Examiner W. J. SHINE, Assistant Examiner US. Cl. X.R. 44-77 

